Abstract: A solid state moderated chemical reaction for use with a heating device comprises the complete reaction between iron powder and the oxidizer sodium chlorate in stoichiometric balance such that the oxygen, rather than being emitted externally to the device, is fully reacted internally in the heating device to a solid oxide. A heating device comprises a heating chamber defining an interior space for receiving and storing a substance to be heated, a heater for use as a source of heat which includes a reaction chamber, a solid state reaction composition disposed within the reaction chamber such that it is physically isolated from and in thermal communication with the interior space of the heating chamber, an activation mechanism in communication with the composition disposed within the reaction chamber, and wherein the reaction composition is inert until the activation mechanism is actuated.